The cover of Michael Crichton's new bestseller State of Fear, which is about the dangers of global warming. In the book, Crichton chooses an organisation dedicated to environment protection as the villain. To convince people of the threat of global warming and to earn money, the organisation plots man-made 'natural' disasters like a tsunami or the collapse of an iceberg in Antarctica. (AFP)

Exeter (England), Feb. 1 (Reuters): Britain, arguing that climate change is now unstoppable, urged the US today to sign up to life-saving cuts in greenhouse gas emissions as environmentalists warned of approaching Armageddon.

Opening a three-day scientific meeting to assess the threat of global warming, environment minister Margaret Beckett said it was vital Washington become more involved.

'A significant impact is already inevitable ' we need to act now to limit the scale of warming in the future and avoid even worse effects,' she said. 'We would like America to engage more fully with these discussions about where we might go.'

America is one of the largest emitters of greenhouse gases like carbon dioxide (CO2), but rejects most scientific opinion that mankind is largely to blame for climate warming and has refused to join the Kyoto Protocol on curbing emissions.

Kyoto, which comes into force on February 16, aims to cut CO2 emissions by developed states by 5.2 per cent below 1990 levels by 2008-12.

President George W. Bush wants a less stringent target.

Washington's aim is to cut the amount of greenhouse gas emissions for every dollar of economic output by 18 per cent in 2012 compared to 2002.

The economy is likely to grow at a faster pace, meaning overall emissions will rise.

Beckett, who said there was no doubt human activity contributed to climate warming, said she believed there was no hope of persuading Bush to sign up to Kyoto.

What was imperative, she added, was to persuade the American administration and public to examine what to do after 2012.

Outspoken environmental scientist Steve Schneider from Stanford University, California, said he too did not expect Bush ' whose term ends in January 2009 ' to sign up to Kyoto, but that public pressure would force his successor to take action.

'There are quite a lot of people already moving forward on this,' he said, noting changing attitudes even within the business community.

British Prime Minister Tony Blair has pledged to make battling climate change one of the top priorities for his presidency of the Group of Eight rich nations this year.

Scientists at the meeting said not only were forests running out of the ability to be net absorbers of CO2, but that the capacity of oceans to be so was limited.

Scientists have said that two degrees Celsius of warming is already expected.

They have predicted that above that level the warming will push the planet into the unknown as ice caps melt, sea levels rise and weather patterns change at accelerating rates putting entire species and millions of people at risk.

The World Wide Fund for Nature said at the weekend that disastrous climate change could kick in within 20 years, leading to possible wipeout in the Arctic of species like polar bears.

A report by international experts last week described the climate as a ticking bomb, and preliminary results of one study said temperatures could rise by up to 11 degrees Celsius. Scientists from 30 nations at the meeting will try to define what constitutes 'dangerous' levels of warming but will not make policy recommendations.